Victron output dips when over 35A

[noelex 77]

Originally Posted by Training Wheels

I’m thinking of purchasing 2 of the Victron 100/50 controllers. In their manual though, it says for panels in parallel the panels should have a minimum of 36 cells each. My panels have 32 cells with a Voc of 21.6V. Anybody know if the controllers would work?

A Voc of 21.6v is high for a panel with 32 cells. It is not far from the typical results of a 36 cell panel so I think the controller would work without starting late, but it hard to know for sure without trying the combination. I would be inclined to choose different controllers.

The other option is to connect 2 of the 32 cell panels in series. This gives poorer results under isolated shade, especially if the two panels connected together are exposed to different conditions, but the losses are not high for most installations. 32 cell panels on their own can sometimes have a voltage that is too low even ignoring the unusual start up requirments of the Victron. Series connection solves this problem.

[Training Wheels]

Thank you. What different controller would you choose?

[noelex 77]

Originally Posted by Training Wheels

Thank you. What different controller would you choose?

I have never owned one but the Midnite Kid gets very good user reports and looks well designed. It has a 30A rating so you need to check if this enough for your panels.

[kryg]

Thank you, However you did bring up an important observation. Please Correct me if I'm wrong - I understand Lithium battery's are not to be left on float charge ever? Charging needs to be set at in my case 14 to 14.4 Volts. Or as I understand it the lithium battery will become damaged, by over charging on float setting of a solar controller. - From my understanding float charging is one of the lithium battery limitations as the BMS may not be able to controller float charging? If this is the case, It is important to set the solar controller at charger for lithium battery's with no float settings. Is that possible or not with Victron controllers?

Now, I wonder if your heat issues and float differences between one controller per solar panel is out of sync with your other controllers maybe an issue for lithium battery charging, even set on no float setting, that is if one can set it just to charge at at 14 to 14.4 V only with not float kicking in on the Victron controllers? It maybe better to have only one larger capacity controller then a number of smaller ones? Or not?

Originally Posted by noelex 77

Generally one controller per panel will be more efficient and adds some redundancy. It depends on the exact specifications, but with Victrons pricing multiple smaller controllers are often not much more expensive than a larger single unit.

The only limitation is the the units desire to drop to float when the current is less than one amp is a little frustrating when running multiple controllers. I hope Victron include the option to disconnect this feature in future software updates. I will need some more time with system to see how often this feature is reducing the effective power output.

You also need to be careful with the relatively high start up voltage. It is not clear if this is a practical problem when using “12v” panels (I suspect not). My panel voltage is high enough, as is yours, that this not an issue in my installation but it may be in others.

[john61ct]

I use 13.8V as 100%, zero absorb and no float.

But this is to maximize longevity, reduce need to rebalance.

Can't be fully automated except with customizable BMS or other add-on sensor/relays etc.

Layers of protection is key, IMO the "root BMS" protections are only there to protect against front-line gear failing.

[kryg]

Originally Posted by john61ct

I use 13.8V as 100%, zero absorb and no float.

But this is to maximize longevity, reduce need to rebalance.

Can't be fully automated except with customizable BMS or other add-on sensor/relays etc.

Layers of protection is key, IMO the "root BMS" protections are only there to protect against front-line gear failing.

Thank you for your information. this is a first for me. I'm removing 700 ah AGM Battery's which Served me well. To 400 ah lithium, when you say layers of protection what else can I do to protect my investment, and enjoy a trouble free power?

[ReneJK]

1 have 2x 335Wp panels (Voc 54 volts) in parallel with a victron smartsolar 100/50 and have just checked temp as well , the blue part gets up to 43 celsius but I have never seen any throttle back around any amperage , mine is set to 50A charge current

[kryg]

Thank you, your experience is also helpful.

[hzcruiser]

Originally Posted by john61ct

I use 13.8V as 100%, zero absorb and no float.

But this is to maximize longevity, reduce need to rebalance.

Can't be fully automated except with customizable BMS or other add-on sensor/relays etc.

Layers of protection is key, IMO the "root BMS" protections are only there to protect against front-line gear failing.

Yes, 8h at 14.6V as per the setting in the OPs post might not be healthy for the LFPs.

@LoudMusic: you might want to think about changing them


John's settings are the other extreme and I would also set it to zero absorb and no float if my Votronic had that setting...


Now I'm wondering at what bus voltage the SC would start putting out current again? Is there another setting for that?

[LoudMusic]

Originally Posted by hzcruiser

Yes, 8h at 14.6V as per the setting in the OPs post might not be healthy for the LFPs.

@LoudMusic: you might want to think about changing them


John's settings are the other extreme and I would also set it to zero absorb and no float if my Votronic had that setting...


Now I'm wondering at what bus voltage the SC would start putting out current again? Is there another setting for that?

OK at your insistence I backed it off to 14.1v and 4h. But I got my settings from the manufacturer's website. But I do like the idea of battery life longevity ...

[hzcruiser]

Originally Posted by LoudMusic

OK at your insistence I backed it off to 14.1v and 4h. But I got my settings from the manufacturer's website. But I do like the idea of battery life longevity ...

Your boat/battery, your choice. You might want to read up on the recommended SOC for LFPs though. They should not be kept at the extremes (close to 0% and 100%) for long, pre-storage SOC is recommended at around 50% because of that.

[LoudMusic]

My Victron 100/50 is definitely VERY hot when outputting over 30A. I have some computer case fans - can I attach them directly to the Victron's 12v output? That way they turn on when the unit is producing power.

[MikeFergie]

Originally Posted by LoudMusic

I have a new 900Ah lithium install, new 2x350w solar panels, new Victron 100/50 MPPT controller.



If I set the output of the Victron to 35A it will peak at 35A and happily output 35A as long as the Sun is providing enough photons.



If I set it to anything over 35A, even just 36A, it will peak to the set value and within about 15 seconds it will drop to 0A output for a few seconds before ramping up to the set value again, and repeat this cycle.



I've set it to 50A and observed it producing full 50A for the short duration described above both in the VictronConnect app and at my Xantrex battery monitor (minus guestimated usage).



Other settings:



Battery voltage: 12V

Max charge current: 35A

Charger enabled: Yes

Battery preset: User defined

Absorption voltage: 14.60V

Maximum absorption time: 8h 0m

Float voltage: 13.80V

Equalization voltage: 14.40V

Automatic equalization: Disabled

Temperature compensation: Disabled

Low temperature cut-off: Disabled



Has anyone experience behavior like this from a charger, specifically Victron MPPT? Any suggestions on where to start troubleshooting?

I have 2 x 345w sunpower panels and recently changed from 2 x victron Mppt chargers to the same as yours. I have screw connectors as well. Attached is my pic. I get up to 49 amps regularly for lengthily times. So it seems to be some issue with yours, either software or hardware related.

[john61ct]

Originally Posted by LoudMusic

My Victron 100/50 is definitely VERY hot when outputting over 30A. I have some computer case fans - can I attach them directly to the Victron's 12v output? That way they turn on when the unit is producing power.

Yes, in fact bump up the ON voltage so they are only on while charging is active.

[Bleemus]

Originally Posted by LoudMusic

My Victron 100/50 is definitely VERY hot when outputting over 30A. I have some computer case fans - can I attach them directly to the Victron's 12v output? That way they turn on when the unit is producing power.

I did this using a 24v computer fan. Worked perfectly.